Last reviewed 16 Sept 2026 · 6 min read
Pictorial projections
Pictorial projections show an object in one view, displaying its three dimensions — easy to visualise but not ideal for exact dimensions of all features.
| Type | Features |
|---|---|
| Axonometric (orthographic pictorial) | Object inclined to the plane; projectors perpendicular to the plane |
| — Isometric | All three axes equally inclined to the plane — equal foreshortening |
| — Dimetric | Two axes equally inclined |
| — Trimetric | All three axes differently inclined |
| Oblique | One face parallel to the plane (true shape); projectors inclined |
| Perspective | Projectors converge — realistic appearance |
Isometric axes, lines and planes
- Isometric axes — three lines representing the edges of a cube meeting at a corner, 120° apart; one is vertical and two are at 30° to the horizontal.
- Isometric lines — lines parallel to the isometric axes; measured along them.
- Non-isometric lines — lines not parallel to the axes (e.g. inclined edges, diagonals); cannot be measured directly — located by their end points.
- Isometric planes — planes parallel to any two isometric axes (top, front and side faces of the cube).
- A cube in isometric view appears as a regular hexagon outline.
Isometric scale
When a cube is viewed along its body diagonal, all edges are equally foreshortened.
FormulaIsometric scale
Isometric lengths are about 81.6% of true lengths.
Construction of an isometric scale
- Draw a horizontal line; from a point draw lines at 45° (true lengths) and 30° (isometric lengths) above it.
- Mark true divisions on the 45° line.
- From each division, draw vertical lines down to meet the 30° line — these give isometric lengths.